<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
</head>
<body>
    <button id="bt1">按钮1</button>
    <input type="button" name="" id="bt2" value="按钮2">

    <script>
        window.onload=function(){
            document.getElementById("bt1").onclick=function(){
                alert("123");
            }

            $("#bt2").click(function(){
                alert(456);
            })

            $("#bt2").click(function(){
                alert(454656);
            })
        }
    </script>
    
</body>
</html>